In almost every race/ethnic group, immigrants are healthier. Here’s the pattern for infant mortality.

Infant Mortality Rates, by Mother's Place of Birth and Race/Ethnicity: U.S., 2007

Immigrants are often healthier than the average people in the countries they came from, which explains some of this. Among Latinos in particular, researchers refer to the “epidemiological paradox,” by which Latinos’ health is surprisingly good given their economic conditions. Robert Hummer and colleagues, in a 2007 article, offered a succinct description:

…the relatively low levels of education, income, and health insurance coverage among Hispanics compared with non-Hispanic whites is thought to place the former at higher risk for negative health outcomes. However, it is well documented that some Hispanic groups exhibit similar observed death rates compared with the non-Hispanic white population and much lower death rates than the non-Hispanic black population, whom they closely resemble with respect to socioeconomic characteristics. The greatest enigma is exhibited by the Mexican-origin population of the United States. This Hispanic subgroup is characterized by low educational attainment; low health insurance coverage rates; mortality rates similar to non-Hispanic whites; and much more favorable mortality rates than those of non-Hispanic blacks across most of the life course.

A sibling approach would be informative. Is the “born elsewhere” effect persistent across siblings? I wonder if the benefit of a foreign mother declines over time within families and across generations?